Autonomic nervous system (ANS) activity and attention has been assessed in 34 boys with diagnoses in the Disruptive Behavior Disorder (DBD)spectrum (Conduct Disorder, Oppositional Defiant Disorder and/or Attention Deficit Hyperactivity Disorder [ADHD]), selected for their antisocial and disruptive behavior, and in 33 normal control boys. We recorded skin conductance (SC) and heart rate (HR) during a rest period, a series of nonsignal tones, and a simple reaction time (RT) task. Attention was assessed by two RT tasks which have been used extensively in schizophrenia research: 1) Simple RT with constant and variable preparatory intervals, and 2) Simple, choice, and "crossmodal" RT to lights and tones. The DBD boys had higher HR but no differences in SC indices of "arousal." However they had smaller increases in all baseline measures to the onset of the RT task than controls. SC response latencies were shorter in the DBD group despite slower RT. Their SC responses to signal stimuli habituated at a faster rate. These results are different from those obtained previously with more 'pure' ADHD samples. Correlational analyses with behavior ratings suggest that there may be autonomically hyperresponsive and hyporesponsive subgroups who may show clinical differences somewhat oblique to the Conduct Disorder subdiagnosis. In general, the data support the concept of the DBD spectrum. DBD subjects with low levels of metabolites of serotonin, norepinephrine, and dopamine measured from cerebrospinal fluid showed generally elevated ANS Responsivity, particularly in the RT task. The RT tasks showed that DBD boys have particular problems when the timing or modality of the stimulus is uncertain. A 2-year clinical followup of these subjects revealed that low SC level )age corrected) significantly predicted institutionalization. There were similar but nonsignificant trends for low ANS activity to predict poor outcome in this group for other variables. The ANS and attention test are being repeated on a new sample of younger boys all of whom have a diagnosis of ADHS.